Dental crowns are often glued onto tooth stumps by providing either the tooth stump or the crown or both with an adhesive suitable for this purpose and then pressing them onto one another. In order to ensure durability of the adhesive joint it is crucial that the entire areas of the adhesive surfaces are provided with the adhesive. For this purpose, it has been known for long to provide for excess adhesive and to then press the parts to be adhered to one another against each other such that excess adhesive is partially squeezed out to the side and such that it is ensured that the entire surfaces are covered with adhesive in any case.
This measure which has been known for decades is used both with dental cement and with other suitable adhesives.
Care must always be taken that the adhesion both on the surface of the respective tooth and on the opposite surface of the dental restoration has the required quality. Typically, at least the surface of the tooth is etched slightly and agents referred to as adhesion agents are used.
Depending on the material of the dental restoration used different adhesives are used. Particularly with composites, there is a tendency towards light-curable adhesives. They typically ooze out of the adhesive gap all around when the dental restoration is pressed on by means of the predetermined force.
As a matter of fact, this so-called excess adhesive must be removed wherein it is difficult particularly with light-curable adhesives to remove excess adhesive as it tends to smear.
In this respect, it has already been suggested to partially cure the excess adhesive in order to turn it gel-like and be able to simply pull it off. Tests have shown that when conventional light-curing devices are used for this purpose it is, however, difficult to remove the excess adhesive; when the material has cured too strongly, it may be ground only very expensively, or virtually not at all in the interdental spaces, and when the material has cured not sufficiently, it only smears when somebody tries to remove the material.
However, leaving excess adhesive in the mesial/distal direction, that is to say in the interdental spaces, particularly leads to periodontitis very easily as deposits and bacteria may easily collect in narrow inner corners which are difficult to access.